Characterization of gingival matrix proteins was initiated in our laboratory to establish baseline information on the nature of the alterations accompanying inflammatory processes, thereby defining the role of the intercellular macromolecules in periodontal disease. Detailed structural studies at the molecular level of the collagenous and noncollagenous components of gingiva from normal and diseased tissues are in progress to establish the biochemical nature of these components and their physiological role in the maintenance of gingival tissue. Heterogeneity of gingival collagen has been established in the present phase of the project and it is now essential to characterize the new types of tropocollagen subunit alpha-chains and to determine their significance for normal gingival tissue function. The question of modulation in the biosynthetic activity of cells from these tissues will be examined in order to understand the factors which may influence gene expression during inflamatory disease. Our data suggested that the noncollagenous moiety which appeared to be firmly associated with the collagenous component, possibly covalently, showed significant change in composition in diseased tissue. A correlation of the structural alterations in gingival connective tissue macromolecules with histological and clinical manifestations of periodontal disease will provide more information on the molecular basis and etiology of the disease.